Year Number of 1990 375.35 1991 364.98 1992 364.34 1993 364.53 1994 367.94 1995 369.32 1996 360.24 1997 348.9 1998 338.02 1999 332.64 2000 337.49 2001 336.53 2002 341.07 2003 341.08 2004 347.8 2005 354.68 2006 354.37 2007 362.91 2008 368.16 2009 379.24 2010 388.41 2011 391.74 2012 399.19 2013 404.25 2014 409.85 2015 416.56 2016 425.36